Modified atmosphere packaging with base-mounted micro-permeable patch

ABSTRACT

A rigid or semi-rigid MAP container includes a raised cavity in its bottom surface, wherein a macroscopic hole penetrating the container bottom is covered by a semi-permeable patch so as to provide limited gas exchange between the container interior and the surrounding environment. The raised cavity extends to at least one edge of the bottom surface, so that gases can be exchanged with the cavity even when the container is placed on a flat surface. In embodiments, the sides are slanted outward, so that air passages accessible to the cavities are formed between adjacent containers in a stack. The container can be re-sealable, and can include an interior sealant layer. The patch can be naturally semi-permeable, microporous, or microperforated, and can be adhered to the container bottom by an adhesive applied about a perimeter thereof that does not overlap the hole.

FIELD OF THE INVENTION

The invention relates to packaging, and more particularly, to modifiedatmosphere packaging.

BACKGROUND OF THE INVENTION

The quality and shelf-life of many perishable products is criticallydependent on the nature and quality of the packaging in which it iscontained. For many food products, such as meats and cheeses, optimalpreservation is obtained by removing as much atmosphere as possible andhermetically sealing the product. However, fresh produce continues toundergo respiration while being transported and stored, and will quicklyperish and spoil if placed in a hermetically sealed container.

One approach for packaging fresh produce is to use packing that is wellventilated, so that the atmosphere within the container approximates theambient atmosphere, thereby allowing unimpeded respiration by thecontained produce while it is transported and stored. This approachavoids the premature spoilage that can result from hermetic packaging,but does nothing to enhance or prolong the quality and shelf life of theproduce beyond what would be obtained if the produce were not containedin a package.

Another approach is to artificially slow the respiration and othermetabolic processes of produce by refrigeration or other coolingmethods, so that the produce remains alive and fresh, but ages moreslowly. Cooling is certainly an effective means to extend the shelf lifeof produce, but cooling methods can be expensive. Also, it may bedesirable to extend the shelf life of fresh produce beyond what can beaccomplished by cooling alone.

Another approach for extending the shelf life of fresh produce, whichcan be implemented either alone or in combination with cooling, is toenclose the produce in packaging that allows only a very limited rate ofgas exchange between the interior of the package and the surroundingenvironment. By tailoring the gas exchange rate to the specific type andquantity of contained produce, and taking into account the temperatureand other factors, it is possible to induce a modified atmosphere withinthe package, whereby the respiration of the contained produce causes theoxygen level to be reduced and the carbon dioxide level to be increased,thereby slowing the metabolism of the produce and extending its shelflife without causing the contained produce to perish and spoil. Thisapproach is generally referred to as equilibrium modified atmospherepackaging (“EMAP” or simply “MAP” as used herein). The result can beincreased quality and longer shelf life, less waste from spoiledproduce, better inventory control, and appreciable overall savings forthe food industry at both the retail and wholesale levels.

MAP can be implemented in any of several ways. In some instances, MAPcan be achieved simply by selecting an appropriate packaging materialand controlling the thickness of the material so as to provide a limitedpermeability to oxygen and carbon dioxide. However, this approach placessignificant constraints on package size, packaging material, overallpackage strength and durability, and packaging costs. It is thereforeapplicable only to a limited range of circumstances.

In a related approach, part or all of a package can be constructed froma microporous material that provides a well-defined gas permeability.Microporous materials can be created by including small fillerparticles, such as silica or calcium carbonate, in a polymerformulation, and orienting the film in the longitudinal and/or crossdirection so as to create microscopic pores throughout the film.However, the methods by which microporous films are produced limit thetypes and thicknesses of packaging materials that can be used. Also,microporous materials can be prohibitively expensive for use as apackaging material. In addition, these microporous materials are oftenopaque, such that making the entire package from microporous materialcan be unacceptable from a consumer standpoint, where great importanceis given to the observation of the appearance of the fresh produce whenmaking a selection.

Another approach is to use a packaging material that is essentiallyimpermeable to gases, and to penetrate the material with one or more“microperforations,” typically having diameters measuring in the tens ofmicrons to hundreds of microns. For example, microperforations can bemade using pins or a laser during manufacture of a web, and then the webcan be used to form produce bags or film tops for produce trays andother rigid containers. In the case of rigid or semi-rigid trays, thisapproach can be effective for packages that are intended for single use,but the approach is problematic for applications where it is desirableto re-seal a rigid or semi-rigid package after initial use, and toreestablish a modified atmosphere to prolong the shelf life of theremaining contents.

Microperforation can be challenging in cases where it is desirable forthe package to be fully rigid or semi-rigid, and possible re-sealable,because it can be difficult to accurately and consistentlymicro-perforate the walls of a rigid or semi-rigid container, especiallyif the container includes an elastomeric inner sealant layer in additionto the rigid or semi-rigid outer layer. One successful solution ispresented in co-pending application U.S. Ser. No. 14/941,028, filed onNov. 13, 2015, also by the present inventor, which is incorporatedherein by reference in its entirety for all purposes. Nevertheless, thisapproach may not be optimal in all circumstances.

Another MAP approach that is applicable to rigid and semi-rigidcontainers is to provide a single, macroscopic opening or hole,typically a few millimeters to a centimeter in diameter, somewhere inthe container, and then cover the macroscopic opening with amicroperforated or microporous “patch.” This MAP hole and patch approachcan be highly effective, and can be relatively easy and cost-effectiveto implement for rigid and semi-rigid containers. However, finding asuitable location for the hole and patch can be problematic.

The lid of a rigid or semi-rigid container is generally a primarydisplay surface, and so it may be desirable to cover the entire lid witha product identifying and branding label, which would interfere with thepatch. Also, it may be undesirable for esthetic reasons to put the holeand patch on the lid, where they will be highly visible. In addition,the sides of a rigid or semi-rigid container often provide importantvisibility to consumers who wish to view the contents of the package.Accordingly, it may also be undesirable to place the hole and patch on aside of the container. And, of course, placement of the patch and holeon the bottom of the container is problematic, because it is likely thatthe patch will be blocked by whatever surface the package is resting on.

Furthermore, rigid containers are often packed closely together andstacked on top of each other during storage, shipment, and even when ondisplay for sale, making it likely that a patch might be blocked by anadjacent container no matter where the hole and patch are located.

What is needed, therefore, is a rigid modified atmosphere packagingcontainer with a rigid lid having an MAP hole and patch that are notlocated on a highly visible surface and are not likely to be blockedwhen the container is resting on a surface and/or included in a stack ofcontainers.

SUMMARY OF THE INVENTION

A rigid modified atmosphere packaging container with a rigid lid isdisclosed having an MAP hole and patch that are not located on a highlyvisible surface and are not likely to be blocked when the container isresting on a surface and/or included in a stack of containers. Accordingto the present disclosure, a region of the container bottom is raised incomparison to the remainder of the bottom surface, such that an openspace or cavity is created, referred to herein as the MAP cavity. Amacroscopic hole and MAP patch are provided on the bottom of thecontainer inside of the MAP cavity, and is covered by a semi-permeablepatch such as a microperforated or microporous patch that permits alimited gas exchange through the hole.

The MAP cavity extends to an edge of the bottom surface, so that air isreadily exchanged between the MAP cavity and the ambient surroundings.As a result, placement of the container on a flat surface or on top ofanother container does not restrict the exchange of air between the MAPcavity and the surrounding atmosphere.

In embodiments, the sides of the container are slanted inward, so thatair passages are created between the containers when they are arrangedin a stack. As a result, air is easily exchanged between the surroundingair and all of the MAP cavities of all of the containers in the stack.In some embodiments, the MAP cavity extends to more than one bottom edgeof the container.

The present invention is a rigid or semi-rigid container configured formodified atmosphere packaging of produce. The container includes a basehaving a bottom and at least one side joined to the bottom by a bottomedge, a lid removably engageable with the base so as to form a sealtherebetween, a raised region formed in the bottom of the container baseand extending to the bottom edge thereof, so that when the containerbottom is placed on a flat surface the raised region and flat surfaceform a cavity into which air from an environment surrounding thecontainer can enter the cavity by passing under the bottom edge, a holeformed in an upper surface of the raised region and penetrating thecontainer bottom, and a semi-permeable patch installed over the hole andconfigured to permit a limited exchange of gases between an interior ofthe container and the surrounding environment, so that a modifiedatmosphere is created within the container when respiring fresh produceis contained therein.

In embodiments, the lid can be re-engaged with the base after removalthereof so as to re-establish a modified atmosphere within the interiorof the container when fresh produce remains contained

In any of the above embodiments, the side can be slanted outward fromthe bottom edge, so that when the container is placed against a verticalsurface or next to an adjacent container having a similar shape, apassage is formed along the side of the container through which air canflow to the bottom edge and from thence to the patch.

In any of the above embodiments, the patch can be made from a materialthat is naturally semi-permeable to gases, a microporous material, or amaterial that is substantially impenetrable to gases, butmicroperforated so as to allow the limited exchange of gasses.

Any of the above embodiments can further include sealant layers appliedto interior surfaces of the base and lid, the sealant layers beingsealable to each other when the lid is engaged with the base so as toform a hermetically sealed junction therebetween. In some of theseembodiments the sealant layers comprise at least one ofpolyacrylonitrile resin and polyester film.

In any of the above embodiments, the hole can be between 1 mm and 10 mmin diameter.

In any of the above embodiments, the patch can be adhered to the uppersurface of the raised region by an adhesive that is applied to aperimeter of the patch but does not overlap the hole.

And in any of the above embodiments, the raised region can extend to aplurality of bottom edges that join a plurality of sides to thecontainer bottom.

The features and advantages described herein are not all-inclusive and,in particular, many additional features and advantages will be apparentto one of ordinary skill in the art in view of the drawings,specification, and claims. Moreover, it should be noted that thelanguage used in the specification has been principally selected forreadability and instructional purposes, and not to limit the scope ofthe inventive subject matter.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a semi-rigid modified atmospherepackaging container in an embodiment of the present invention shown withthe lid and patch separated from the container body;

FIG. 2 is a perspective view of the semi-rigid modified atmospherepackaging container of FIG. 1 shown with the lid and patch installed onthe container body;

FIG. 3 is a perspective view of two containers as shown in FIG. 2stacked on top of each other;

FIG. 4A is an end view of the embodiment of FIG. 2, shown without thepatch;

FIG. 4B is an end view of the embodiment of FIG. 4A, shown with thepatch;

FIG. 5 is a side view of a stack of the containers of FIG. 2; and

FIG. 6 is a perspective view of a container in an embodiment wherein theMAP cavity extends to all bottom edges of the container.

DETAILED DESCRIPTION

With reference to FIGS. 1 and 2, a modified atmosphere packagingcontainer 100 having a rigid body 102 and a rigid lid 104 is disclosedthat includes a macroscopic hole 106 and MAP patch 108 that are notlocated on a highly visible surface and are not likely to be blockedwhen the container 100 is resting on a surface or included in a stack ofcontainers. According to the present disclosure, the macroscopic hole106 is provided on the bottom of the container body 102, and is coveredby the microporous patch 108. In embodiments, the hole 106 is between 1mm and 10 mm in diameter. FIG. 1 is a perspective view of a container100 in an embodiment of the invention shown with the lid 104 removed,and the patch 108 not yet installed. FIG. 2 is a perspective view of thecontainer of FIG. 1 shown with the microporous patch 108 installed.

The patch 108 can include a material that is naturally gas permeable ormicroporous, or it can be made from a gas impervious material that hasbeen microperforated by pins or by a laser. It can be attached to thebottom of the container body 102 by an adhesive that has been appliedabout a perimeter of the patch 108, so that the adhesive surrounds thehole 106 but does not interfere with gas exchange through the region ofthe patch 106 that is/are directly over the hole 106.

As shown in FIGS. 1 and 2, the macroscopic opening 106 andmicroperforated patch 108 are located in a region 110 of the containerbottom that is raised as compared to the remainder of the bottomsurface, such that an open space or cavity is created in the region 110where the opening 106 and patch 108 are located. This open space orcavity 110, referred to herein as the MAP cavity 110, extends to an edge112 of the bottom surface, so that air 200 is readily exchanged betweenthe MAP cavity 110 and the ambient surroundings, even when the container100 is placed on a flat surface, or stacked on top of another containeras shown in FIG. 3.

FIGS. 4A and 4B are end views of the container 100 of FIGS. 1 and 2. Itcan be seen that the MAP cavity 110 is open to the bottom edge 112 ofthe container. In FIG. 4A, the container is shown without the patch 108installed, and in FIG. 4B the container is shown with the patch 108installed.

In the embodiments of FIGS. 1 through 4B, the sides 400 of the container100 are slanted inward. With reference to FIG. 5, this slanted sideconfiguration creates air passages 500 between the containers 100 whenthey are arranged in a stack. As a result, air 200 is easily exchangedbetween the surrounding environment and all of the MAP cavities 110 ofall of the containers 100 in the stack.

In the embodiments of FIGS. 1-5, the MAP cavity 110 extends only to oneedge 112 of the container bottom. In the embodiment of FIG. 6, the MAPcavity 110 extends to all of the bottom edges of the cavity, allowingfor additional access of ambient air to the patch 108.

The foregoing description of the embodiments of the invention has beenpresented for the purposes of illustration and description. Each andevery page of this submission, and all contents thereon, howevercharacterized, identified, or numbered, is considered a substantive partof this application for all purposes, irrespective of form or placementwithin the application.

This specification is not intended to be exhaustive. Although thepresent application is shown in a limited number of forms, the scope ofthe invention is not limited to just these forms, but is amenable tovarious changes and modifications without departing from the spiritthereof. One or ordinary skill in the art should appreciate afterlearning the teachings related to the claimed subject matter containedin the foregoing description that many modifications and variations arepossible in light of this disclosure. Accordingly, the claimed subjectmatter includes any combination of the above-described elements in allpossible variations thereof, unless otherwise indicated herein orotherwise clearly contradicted by context. In particular, thelimitations presented in dependent claims below can be combined withtheir corresponding independent claims in any number and in any orderwithout departing from the scope of this disclosure, unless thedependent claims are logically incompatible with each other.

I claim:
 1. A rigid or semi-rigid container configured for modifiedatmosphere packaging of produce, the container comprising: a base havinga bottom and at least one side joined to the bottom by a bottom edge; alid removably engageable with the base so as to form a sealtherebetween; a raised region formed in the bottom of the container baseand extending to the bottom edge thereof, so that when the containerbottom is placed on a flat surface the raised region and flat surfaceform a cavity into which air from an environment surrounding thecontainer can enter the cavity by passing under the bottom edge; a holeformed in an upper surface of the raised region and penetrating thecontainer bottom; and a semi-permeable patch installed over the hole andconfigured to permit a limited exchange of gases between an interior ofthe container and the surrounding environment, so that a modifiedatmosphere is created within the container when respiring fresh produceis contained therein.
 2. The container of claim 1, wherein the lid canbe re-engaged with the base after removal thereof so as to re-establisha modified atmosphere within the interior of the container when freshproduce remains contained
 3. The container of claim 1, wherein the sideis slanted outward from the bottom edge, so that when the container isplaced against a vertical surface or next to an adjacent containerhaving a similar shape, a passage is formed along the side of thecontainer through which air can flow to the bottom edge and from thenceto the patch.
 4. The container of claim 1, wherein the patch is madefrom a material that is naturally semi-permeable to gases.
 5. Thecontainer of claim 1, wherein the patch is made from a microporousmaterial.
 6. The container of claim 1, wherein the patch is made from amaterial that is substantially impenetrable to gases, the patch beingmicroperforated so as to allow the limited exchange of gasses.
 7. Thecontainer of claim 1, further comprising sealant layers applied tointerior surfaces of the base and lid, the sealant layers being sealableto each other when the lid is engaged with the base so as to form ahermetically sealed junction therebetween.
 8. The container of claim 7,wherein the sealant layers comprise at least one of polyacrylonitrileresin and polyester film.
 9. The container of claim 1, wherein the holeis between 1 mm and 10 mm in diameter.
 10. The container of claim 1,wherein the patch is adhered to the upper surface of the raised regionby an adhesive that is applied to a perimeter of the patch but does notoverlap the hole.
 11. The container of claim 1, wherein the raisedregion extends to a plurality of bottom edges that join a plurality ofsides to the container bottom.